fix: error when install script target directory does not exist

Add install.sh to the main repository (previously only in the now-archived
chainloop-dev/docs repo) with the following improvements:

1. Add early validation after argument parsing to verify the --path
   installation directory exists before downloading anything. Provides a
   clear error message with a suggested fix (mkdir -p) instead of failing
   silently or showing confusing sudo errors.

2. Improve the install step to provide proper error output when the binary
   installation fails, instead of silently redirecting stderr to /dev/null.

Fixes #2977

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Signed-off-by: Vibhav Bobade <vibhav.bobde@gmail.com>

Author: waveywaves

install.sh

@@ -0,0 +1,225 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# Based on https://developer.fermyon.com/ install script thanks!
+# Fancy colors for output
+RED='\033[0;31m'
+GREEN='\033[0;32m'
+NC='\033[0m' # No Color aka reset
+
+# Version to install. Defaults to latest or set by --version or -v
+VERSION=""
+FORCE_VERIFICATION=false
+INSTALL_PATH=/usr/local/bin
+PUBLIC_KEY_URL="https://raw.githubusercontent.com/chainloop-dev/docs/c5b7b9be051d8d3b9f48153c6e3ccf569e6990e8/static/cosign-releases.pub"
+
+# Print in colors - 0=green, 1=red, 2=neutral
+# e.g. fancy_print 0 "All is great"
+fancy_print() {
+    if [[ $1 == 0 ]]; then
+        echo -e "${GREEN}${2}${NC}"
+    elif [[ $1 == 1 ]]; then
+        echo -e "${RED}${2}${NC}"
+    else
+        echo -e "${2}"
+    fi
+}
+
+
+# Function to print the help message
+print_help() {
+    fancy_print 2 ""
+    fancy_print 2 "---- Chainloop Installer Script ----"
+    fancy_print 2 "This script installs Chainloop in the current directory."
+    fancy_print 2 ""
+    fancy_print 2 "Command line arguments"
+    fancy_print 2 "--version or -v       Provide what version to install e.g. \"v0.5.0\"."
+    fancy_print 2 "--path                Installation path (default: /usr/local/bin)"
+    fancy_print 2 "--force-verification  Force signature verification of the binary with cosign."
+    fancy_print 2 "--help or -h          Shows this help message"
+}
+
+# Function used to check if utilities are available
+require() {
+    if ! hash "$1" &>/dev/null; then
+        fancy_print 1 "'$1' not found in PATH. This is required for this script to work."
+        exit 1
+    fi
+}
+
+# check if a command exist
+is_command() {
+  command -v "$1" >/dev/null
+}
+
+# checksums.txt file validation
+# example: check_sha256 "${TMP_DIR}" checksums.txt
+validate_checksums_file() {
+  cd "$1"
+  if is_command sha256sum; then
+    sha256sum --ignore-missing --quiet --check "$2"
+  elif is_command shasum; then
+    shasum -a 256 --ignore-missing --quiet --check checksums.txt
+  else
+    fancy_print 1 "We were not able to verify checksums. Commands sha256sum, shasum are not found."
+    return 1
+  fi
+  fancy_print 2 "Checksum OK\n"
+}
+
+# Parse input arguments
+while [[ $# -gt 0 ]]; do
+    case $1 in
+    '--version' | -v)
+        shift
+        if [[ $# -ne 0 ]]; then
+            # Remove v prefix if provided
+            VERSION="$(echo ${1} | sed -e 's/^v\(.*\)/\1/')"
+        else
+            fancy_print 1 "Please provide the desired version. e.g. --version v0.5.0"
+            exit 0
+        fi
+        ;;
+    '--help' | -h)
+        shift
+        print_help
+        ;;
+    '--force-verification')
+        FORCE_VERIFICATION=true
+        ;;
+    '--path')
+        shift
+        INSTALL_PATH=$1
+        ;;
+    *)
+        fancy_print 1 "Unknown argument ${1}."
+        print_help
+        exit 1
+        ;;
+    esac
+    shift
+done
+
+# Validate that the installation path exists
+if [ ! -d "${INSTALL_PATH}" ]; then
+    fancy_print 1 "The installation path '${INSTALL_PATH}' does not exist. Please create it first with: mkdir -p ${INSTALL_PATH}"
+    exit 1
+fi
+
+# Check all required utilities are available
+require curl
+require tar
+require uname
+
+if ! hash "cosign" &>/dev/null; then
+    if [[ $FORCE_VERIFICATION = true ]]; then
+        fancy_print 1 "--force-verification was set but Cosign is not present. Please download it from here https://docs.sigstore.dev/cosign/installation"
+        exit 1
+    fi
+fi
+
+# Check if we're on a supported system and get OS and processor architecture to download the right version
+UNAME_ARC=$(uname -m)
+
+case $UNAME_ARC in
+"x86_64")
+    ARC="amd64"
+    ;;
+"arm64"|"aarch64")
+    ARC="arm64"
+    ;;
+*)
+    fancy_print 1 "The Processor type: ${UNAME_ARC} is not yet supported by Chainloop."
+    exit 1
+    ;;
+esac
+
+case $OSTYPE in
+"linux-gnu"*)
+    OS="linux"
+    ;;
+"darwin"*)
+    OS="darwin"
+    ;;
+*)
+    fancy_print 1 "The OSTYPE: ${OSTYPE} is not supported by this script."
+    exit 1
+    ;;
+esac
+
+# Check desired version. Default to latest if no desired version was requested
+if [[ $VERSION = "" ]]; then
+   VERSION=$(curl -so- https://github.com/chainloop-dev/chainloop/releases | grep 'href="/chainloop-dev/chainloop/releases/tag/v[0-9]*.[0-9]*.[0-9]*\"' | sed -E 's/.*\/chainloop-dev\/chainloop\/releases\/tag\/(v[0-9\.]+)".*/\1/g' | head -1)
+   # Remove v prefix
+   VERSION="$(echo ${VERSION} | sed -e 's/^v\(.*\)/\1/')"
+fi
+
+# Temporary directory, works on Linux and macOS
+TMP_DIR=$(mktemp -d 2>/dev/null || mktemp -d -t 'mytmpdir')
+FILENAME="chainloop-cli-${VERSION}-${OS}-${ARC}.tar.gz"
+# Constructing download FILE and URL
+FILE="${TMP_DIR}/${FILENAME}"
+
+BASE_URL="https://github.com/chainloop-dev/chainloop/releases/download/v${VERSION}"
+
+URL="${BASE_URL}/${FILENAME}"
+# Download file, exit if not found - e.g. version does not exist
+fancy_print 0 "Step 1: Downloading: ${FILENAME}"
+curl -fsL $URL -o $FILE || (fancy_print 1 "The requested file does not exist: ${URL}"; exit 1)
+fancy_print 0 "Done...\n"
+
+# Get checksum file and check it
+fancy_print 0 "Step 1.2: Verifying checksum"
+CHECKSUM_FILENAME=checksums.txt
+CHECKSUM_FILE="${TMP_DIR}/${CHECKSUM_FILENAME}"
+URL="${BASE_URL}/${CHECKSUM_FILENAME}"
+curl -fsL $URL -o ${CHECKSUM_FILE} || (fancy_print 1 "The requested file does not exist: ${URL}"; exit 1)
+validate_checksums_file "${TMP_DIR}" checksums.txt
+
+# Verify checksum file signature
+if hash "cosign" &>/dev/null; then
+    # Constructing download FILE and URL
+    SIGNATURE_FILE="${CHECKSUM_FILENAME}.sig"
+    URL="${BASE_URL}/${SIGNATURE_FILE}"
+    # Download file, exit if not found - e.g. version does not exist
+    fancy_print 0 "Step 1.3: Verifying signature"
+    curl -fsOL $URL || (fancy_print 1 "The requested file does not exist: ${SIGNATURE_FILE}"; exit 1)
+    cosign verify-blob \
+        --key ${PUBLIC_KEY_URL} \
+        --signature ${SIGNATURE_FILE} \
+        ${CHECKSUM_FILE}
+
+    rm $SIGNATURE_FILE
+else
+    fancy_print 2 "\nSignature verification skipped, cosign is not installed\n"
+fi
+
+# Decompress the file
+fancy_print 0 "Step 2: Decompressing: ${FILE}"
+BINARY_NAME="chainloop"
+BINARY="${TMP_DIR}/chainloop"
+(cd ${TMP_DIR} && tar xf $FILE)
+fancy_print 0 "Done...\n"
+
+# Install
+fancy_print 0 "Step 3: Installing: ${BINARY_NAME} in path ${INSTALL_PATH}"
+if ! install "${BINARY}" "${INSTALL_PATH}/" 2>/tmp/chainloop_install_err; then
+    fancy_print 2 "Install without sudo failed, trying with sudo..."
+    if ! sudo install "${BINARY}" "${INSTALL_PATH}/"; then
+        fancy_print 1 "Failed to install '${BINARY_NAME}' to '${INSTALL_PATH}/'. Please check permissions."
+        cat /tmp/chainloop_install_err 2>/dev/null
+        rm -f /tmp/chainloop_install_err
+        exit 1
+    fi
+fi
+rm -f /tmp/chainloop_install_err
+
+# Remove the compressed file
+fancy_print 0 "Step 4: Cleanup"
+rm -r ${TMP_DIR}
+fancy_print 0 "Done...\n"
+${INSTALL_PATH}/${BINARY_NAME} version
+
+
+fancy_print 2 "Check here for the next steps: https://docs.chainloop.dev\n"
+fancy_print 2 "Run '${BINARY_NAME} auth login' to get started"